This invention relates to a method and apparatus for transversely cutting elongated material such as superposed web plies and, more particularly, to the use of a unique orbiting saw for cutting through elongated web material such as toilet tissue and toweling logs or stacked superposed plies such as folded tissues and towels.
In the production of web rolls such as toilet paper and toweling, a jumbo sized roll (often 4 to 6 feet in diameter and upwards of 6 feet in length) was unwound, transversely perforated, longitudinally slit and rewound to provide the well known retail size rolls. This was done continuously and automatically in "rewinders" such as can be seen in U.S. Pat. No. 2,769,600. In the late 1950's and early 1960's, it was realized that problems could arise because of the longitudinal slitting, i.e., slicing the relatively wide web into 41/2 inch widths (a square of toilet paper conventionally being 41/2 by 41/2 inches). If the wide sheet were imperfect in spots (sometimes characterized as "fish-eyes" and referring to large holes in the paper) the entire rewinder had to be shut down because of discontinuity in the winding. Therefore, the longitudinal slitting during the rewinding was eliminated and the rewound, transversely perforated roll or log transferred from the rewinder to a log saw. Because automation was important to maintain high production rates and low economy, the log saws were integrated into the rewinder line.
Among the first log saws were the so-called "Gilbertville" saws employing a circular disc having a peripheral cutting edge which oscillated back and forth across the path of the wound log emanating from the rewinder. The Gilbertville saw can be seen in U.S. Pat. Nos. 2,752,999 and 2,766,566. As the rewinder speeds increased, a new variety of log saw appeared and gained popularity, this being the "orbiting" saw--see Renard U.S. Pat. No. 3,213,721.
As rewinder speeds became greater and greater--thereby requiring more logs to be sawed per unit of time, various improvements were made in the orbiting saws such as the variable-speed orbit saw of U.S. Pat. Nos. 3,213,734 and 3,292,470. In an effort to keep up with the high volume output of rewinders, the art even went to transversely cutting four logs simultaneously, i.e., four lanes of logs being advanced through the sawing station--see U.S. Pat. No. 3,905,260. However, this involved expensive and complicated indexing machinery, i.e., apparatus for stepping the logs or stacks into the sawing station for each cut.
With the increased demand for paper rolls and stacks and the ability to deliver the same at high volume from rewinders, it became clear that the existing orbital saws could not maintain the pace. Of course, additional saws could be placed in parallel but this created material handling problems, occupied valuable space, and was generally inefficient.